When is an iPad not an iPad? Maybe when it runs apps in their own resizable windows just like your laptop, which is exactly what Quasar, an app for jailbroken iPads, does.
Developed by Pedro Franceschi, Quasar allows you to view multiple apps at the same time; resize windows; switch orientation, and rearrange apps on the screen. From the video, it seems to be pretty slick.
It might be particularly useful for apps that are technically only available for iPhone, as they can be run at their native size. Of course, you do have to be running a jailbroken iPad to use it, but if you are, it costs £6.50 from the Cydia Store.